Blockade of catecholamine-induced growth by adrenergic and dopaminergic receptor antagonists in Escherichia coli O157:H7, Salmonella enterica and Yersinia enterocolitica

Table 5 α-Adrenergic antagonists do not inhibit the ability of catecholamines to -mediate bacterial uptake of Tf-complexed iron.

	Uptake of ⁵⁵ Fe from ⁵⁵ Fe-Tf (CPM)
Culture Conditions	Y. enterocolitica	E. coli O157:H7	S. enterica
No additions (control)	363 (14)	848 (23)	910 (33)
50 μM NE	2736 (13)	21343 (1185)	22867 (848)
50 μM NE plus 200 μM phentolamine	2375 (98)	22333 (1154)	24843 (141)
50 μM NE plus 200 μM phenoxybenzamine	2482 (93)	20205 (1058)	22106 (676)
50 μM NE plus 200 μM prazosin	3133 (37)	23189 (1185)	21109 (625)
50 μM NE plus 100 μM Fe	613 (16)	3870 (57)	6617 (246)
100 μM Epi	1759 (101)	23975 (1164)	21006 (1045)
100 μM Epi plus 200 μM phentolamine	2133 (37)	28301 (262)	21991 (827)
100 μM Epi plus 200 μM phenoxybenzamine	1987 (37)	22151 (1148)	21452 (208)
100 μM Epi plus 200 μM prazosin	1887 (104)	24682 (1059)	20403 (894)
100 μM Epi plus 100 μM Fe	238 (13)	2642 (123)	1889 (66)

The table shows NE and Epi-mediated bacterial uptake of ⁵⁵Fe from ⁵⁵Fe-labelled transferrin in the presence of concentrations of α-adrenergic antagonists inhibitory to NE and Epi growth induction. Exponential cultures of the bacteria shown were inoculated at approximately 2 × 10⁸ CFU/ml into triplicate 1-ml aliquots of serum-SAPI containing the compounds shown in the Table plus 2.7 × 10⁵ cpm of ⁵⁵Fe-labelled transferrin. After incubation for 6 hours bacteria were harvested, washed and measured for cellular uptake of ⁵⁵Fe from ⁵⁵Fe-transferrin (CPM) by scintillation counting, as described in Materials and Methods. Analysis of growth levels revealed no significant differences in growth levels between control and catecholamine/antagonist supplemented cultures. The values shown represent the means of bacterial ⁵⁵Fe incorporation from triplicate 1 ml uptake assays; standard deviations are shown in brackets.

ISSN: 1471-2180